Sudden death is defined as a natural death that occurs suddenly. Cardiovascular, respiratory, and central nervous system diseases, drugs, alcohol abuse, bleeding allergies, and poisoning can all cause sudden death, but sudden cardiac death is more common. Sudden cardiac death is a sudden, natural death due to cardiac causes. Patients usually die within one hour of the onset of symptoms. The most common cause of sudden cardiac death is fatal malignant ventricular arrhythmias, including ventricular tachycardia and ventricular fibrillation.